[ Sorry for not looking at this thread sooner ] Bharath Rupireddy <bharath.rupireddyforpostg...@gmail.com> writes: > Currently, $subject is not allowed. We do plan the mat view query > before every refresh. I propose to show the explain/explain analyze of > the select part of the mat view in case of Refresh Mat View(RMV).
TBH, I think we should reject this. The problem with it is that it binds us to the assumption that REFRESH MATERIALIZED VIEW has an explainable plan. There are various people poking at ideas like incremental matview updates, which might rely on some implementation that doesn't exactly equate to a SQL query. Incremental updates are hard enough already; they'll be even harder if they also have to maintain compatibility with a pre-existing EXPLAIN behavior. I don't really see that this feature buys us anything you can't get by explaining the view's query, so I think we're better advised to keep our options open about how REFRESH might be implemented in future. regards, tom lane